reports that you can now switch your blog to Blogger Beta if you use FTP. I don't, so I don't know how well it works but they say they've tested it on the four most popular hosting providers for Blogger such as Your-Site (I wonder what the others are?).
But note that: "We do recommend that, before you switch, you create an account on the new version of Blogger by signing in with a Google Account at http://beta.blogger.com/. Try creating a test blog there and verifying that it can publish to your hosting provider. You can then switch your current Blogger blog to this Google Account. Or, just ask around on the Blogger Help Group to find out if other people have had success publishing to your particular hosting provider.
If publishing to your hosting provider does not work — especially if it did work with the current Blogger — send a message to Blogger Support. We want to fix all FTP publishing problems that we are able to.
Extra tip: ask your hosting provider if they support SFTP. If they do, you should use it instead of FTP. It’s more secure than FTP and we’ve found that it will often work when FTP does not."
Also be warned (from the Known Issues Blog) that if you switch to Blogger Beta, your most recently updated 25 posts will appear as new in feed aggregators.
I still have no ability to switch from classic Blogger on my Dashboard, presumably as my blog is large. Just as well as I've not had a chance to get to grips with the new nuts & bolts of Beta yet!